The 24-year-old French winger has scored seven goals in all competitions for Wolves this season following a summer move from Saint-Etienne.
"If he doesn't become a top player, I'll be surprised," Saunders told the Birmingham Mail. "We are going to have a job keeping hold of him.
"I've watched him every day in training and it is not a fluke what he does in games."
A number of Premier League clubs are thought to be keen on capturing Sako in the January transfer window.